1. Field of Invention
This invention pertains to a method and device for evaluating the performance of a ball in flight, and more particularly for evaluating the effects of wear and tear on the air resistance of the ball.
2. Description of the Prior Art
The resurgence of interest in the country in physical activities such as tennis and similar sports have led to improved sporting goods which last longer and perform better. Similarly a need developed for auxiliary equipment for monitoring the performance of the sporting equipment. For example in certain sports balls are projected through the air at high speed. The behavior of these balls is very much dependent on their surface characteristics and as the wear and tear associated with normal usage changes these surface characteristics, the behavior of the balls in flight changes also. This is especially true for tennis balls which initially have a 1/8 to 3/16 inch surface nap. Because of this nap, tennis players are able to impart a spin on the ball which makes the ball change direction in mid-flight and bounce in unpredictable directions. However as the nap wears off it becomes harder to spin the ball. Therefore it is important for a tennis player to know the condition of different balls. Furthermore balls made by different manufacturers have different sized naps. The number and thickness of fibers per unit area also changes not only from one manufacturer to another but from one quality of ball to another even if made by the same manufacturer. Obviously both the density and the thickness of the fibers affect the characteristics of the ball. Yet until now the only way to determine these characteristics was by subjective visual inspection and comparison. However this was found to be unsatisfactory especially if the balls of different manufacturers are compared.